GB/T 17140-1997 standard for the determination of lead and cadmium content in soil, using KI-MIBK extraction flame Atomic absirption spectroscopy-tometry, AAS. First, the soil sample is digested to dissolve lead and cadmium, and the lead and cadmium are extracted and enriched by potassium iodide (KI) and methyl isobutyl ketone (MIBK). After that, with the help of flame atomic absorption spectrophotometer, the Absorbance was determined according to the absorption characteristics of lead and cadmium atoms on specific wavelengths of light, and then the content of lead and cadmium in the soil was accurately obtained, which provided an effective detection method for soil mass assessment and pollution monitoring.